R Nuclear Reactor – Savannah River Site, South Carolina

In December 1953, R Reactor became Savannah River Site's first production reactor when it was "taken to critical" (meaning that full operation resulted in a sustained nuclear chain reaction). The R Reactor served as a prototype for the four other SRS reactors: P, L, K, and C. It produced plutonium-238, plutonium-239, and tritium - all ingredients of nuclear bombs.

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The tall block shown here is the "actuator tower" which sits above the reactor core. The core itself sinks 40 feet below ground level; actuator parts (such as fuel rods) were lowered into the core once the reactor became operational or "critical." The reactor's adjoining sections were used for assembly of fuel rods, disassembly of fuel rods, and purification of reactor cooling water. The cylinder's concrete stack provided an emergency exhaust for the building and ground-level employees in the case of contamination.

In 1963, after ten years of operation, a defective fuel rod released Cesium 137 and other chemicals into the man-made Par Pond, situated next to the reactor.1 R Reactor also suffered from several unrelated leaks and was in an overall state of degeneration. Then, in his January 1964 State of the Union Address, President Johnson called for an immediate reduction in the arms race. The reactor closed June 17, 1964 - just six months later.

R-Reactor is now in a state of decommissioning or decontamination. The final step in the decommissioning process is to fill the reactors with a low-density cement injected with foaming agents. This turns the decommissioned reactors into solid, impenetrable blocks. This process was completed in 2011. You can read about this and other SRS cleanup projects funded by the Recovery Act here.